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| Titel |
CFD modeling of a vehicle exhaust laboratory sampling system: sulfur-driven nucleation and growth in diluting diesel exhaust |
| VerfasserIn |
M. Olin, T. Rönkkö, M. Dal Maso |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 9 ; Nr. 15, no. 9 (2015-05-13), S.5305-5323 |
| Datensatznummer |
250119709
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| Publikation (Nr.) |
 copernicus.org/acp-15-5305-2015.pdf |
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| Zusammenfassung |
| A new exhaust aerosol model CFD-TUTEAM (Tampere University of Technology
Exhaust Aerosol Model for Computational Fluid Dynamics) was developed. It is
based on modal aerosol dynamics modeling with log-normal assumption of
particle distributions. The model has an Eulerian sub-model providing
detailed spatial information within the computational domain and a
computationally less expensive, but spatial-information-lacking, Lagrangian
sub-model. Particle formation in a laboratory sampling system that includes a
porous tube-type diluter and an aging chamber was modeled with CFD-TUTEAM.
The simulation results imply that over 99% of new particles are formed
in the aging chamber region because the nucleation rate remains at a high level in
the aging chamber due to low dilution ratio and low nucleation exponents. The
nucleation exponents for sulfuric acid in sulfuric-acid–water nucleation
ranging from 0.25 to 1 appeared to fit best with measurement data, which are
the same values as obtained from the slopes of the measured volatile
nucleation mode number concentration vs. the measured raw exhaust sulfuric
acid concentration. These nucleation exponents are very low compared to the
nucleation exponents obtained from the classical nucleation theory of binary
sulfuric-acid–water nucleation. The values of nucleation exponent lower than
unity suggest that other compounds, such as hydrocarbons, might have a
significant role in the nucleation process. |
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